\(\frac{6}{7}+\frac{5}{7.\left(-5\right)}=\frac{-1}{28.\left(-2\right)^2}\)
\(< =>\frac{6\left(-35\right)}{7\left(-35\right)}+\frac{35}{7\left(-35\right)}=-\frac{1}{28.4}=-\frac{1}{112}\)
\(< =>\frac{5\left(-35\right)}{7\left(-35\right)}=-\frac{1}{112}\)
\(< =>\frac{1}{112}=\frac{1}{2.\left(-35\right)}\)
\(< =>-35.2=112\)(vô lý)